Coated particles and related methods

ABSTRACT

Coated particles comprise a core particle comprising a superhard material and having an average diameter of between 1 μm and 500 μm. A coating material is adhered to and covers at least a portion of an outer surface of the core particle, the coating material comprising an amine terminated group. A plurality of nanoparticles selected from the group consisting of carbon nanotubes, nanographite, nanographene, non-diamond carbon allotropes, surface modified nanodiamond, nanoscale particles of BeO, and nanoscale particles comprising a Group VIIIA element is adhered to the coating material.

CROSS-REFERENCE TO RELATED APPLICATIONS

The subject matter of this application is related to the subject matterof provisional U.S. Patent Application Ser. No. 61/408,382, which wasfiled Oct. 29, 2010 and is entitled “Graphene-Coated Diamond Particles,Polycrystalline Compacts, Drill Bits, and Compositions ofGraphene-Coated Diamond Particles, and Methods of Forming Same,” thedisclosure of which is incorporated herein in its entirety by thisreference. The subject matter of this application is also related to thesubject matter of nonprovisional U.S. patent application Ser. No.13/283,021, which was filed Oct. 27, 2011, which claims the benefit ofprovisional U.S. Patent Application Ser. No. 61/408,382.

FIELD

Embodiments of the disclosure relate generally to coated particles,methods of forming coated particles, and methods of formingpolycrystalline compacts from coated particles. Specifically,embodiments of the disclosure relate to particles of superhard materialthat have nanoparticles coated thereon.

BACKGROUND

Superhard materials have proven to be useful in a wide variety ofapplications. For example, cutting elements used in earth-boring toolsoften include a polycrystalline diamond (PCD) material, which may beused to form polycrystalline diamond cutters (often referred to as“PDCs”). Such polycrystalline diamond cutting elements areconventionally formed by sintering and bonding together relatively smalldiamond grains or crystals under conditions of high temperature and highpressure in the presence of a catalyst (e.g., cobalt, iron, nickel, oralloys and mixtures thereof) to form a layer of polycrystalline diamondmaterial on a cutting element substrate. These processes are oftenreferred to as high temperature/high pressure (or “HTHP”) processes. Thecutting element substrate may comprise a cermet material (i.e., aceramic-metal composite material) comprising a plurality of particles ofhard material in a metal matrix, such as, for example, cobalt-cementedtungsten carbide. In such instances, catalyst material in the cuttingelement substrate may be drawn into the diamond grains or crystalsduring sintering and catalyze formation of a diamond table from thediamond grains or crystals. In other methods, powdered catalyst materialmay be mixed with the diamond grains or crystals prior to sintering thegrains or crystals together in an HTHP process.

Earth-boring tools for forming wellbores in subterranean earthformations that may include a plurality of cutting elements secured to abody include, for example, fixed-cutter earth-boring rotary drill bits(also referred to as “drag bits”). Such fixed-cutter bits include aplurality of cutting elements that are fixedly attached to a bit body ofthe drill bit, conventionally in pockets formed in blades and otherexterior portions of the bit body. Other earth-boring tools may includerolling cone earth-boring drill bits, which include a plurality ofcutters attached to bearing pins on legs depending from a bit body. Thecutters may include cutting elements (sometimes called “teeth”) milledor otherwise formed on the cutters, which may include hardfacing on theouter surfaces of the cutting elements, or the cutters may includecutting elements (sometimes called “inserts”) attached to the cutters,conventionally in pockets formed in the cutters. Cutting elements thatinclude superhard materials increase the useful life of the earth-boringtools to which they are attached because the superhard materialsincrease the strength and abrasion resistance of the tools.

Some superhard materials have desirable properties that render themuseful in still other applications. For example, the high strength andabrasion resistance of such materials renders them useful in grinding,polishing, and machining applications. Increased thermal conductivity ofsome superhard materials renders them useful as particles dispersed inlubricants, such as motor and pump oils, because such lubricants oftenserve to cool the parts they lubricate. Furthermore, increasedelectrical conductivity of some superhard materials renders them usefulas fillers in polymers and elastomers, where increased electricalconductivity in at least some portion of the polymers and elastomers isdesirable.

Some attempts have been made to enhance or alter the properties ofsuperhard materials through layering other materials thereon. Forexample, Core-Shell Diamond as a Support for Solid-Phase Extraction andHigh-Performance Liquid Chromatigraphy, 82 Analytical Chem. 4448 (Jun.1, 2010), by Gaurav Saini, David S. Jensen, Landon A. Wiest, Michael A.Vail, Andrew Dadson, Milton L. Lee, V. Shutthanandan, and Matthew R.Linford discloses, among other things, layer-by-layer deposition of anamine-containing polymer and nanodiamond on an amine functionalizedmicrodiamond.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming that which is regarded as the present invention,various features and advantages of embodiments of the disclosure may bemore readily ascertained from the following description of embodimentsof the disclosure when read in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a cross-sectional view of a core particle;

FIG. 2 depicts a cross-sectional view of the core particle of FIG. 1after being coated with a coating material;

FIG. 3 illustrates a cross-sectional view of the coated core particle ofFIG. 2 after nanoparticles have been disposed on the coating material;

FIG. 4 is a cross-sectional view of the coated core particle of FIG. 3after coating the nanoparticles with another coating;

FIG. 5 depicts a cross-sectional view of the coated core particle ofFIG. 4 after other nanoparticles have been disposed on the othercoating;

FIG. 6 illustrates a cross-sectional view of an alternative embodimentof the nanoparticles shown in FIG. 5;

FIG. 7 is a cross-sectional view of another embodiment of the coatedcore particle shown in FIG. 5 wherein the other nanoparticles aredisposed directly on the first nanoparticles;

FIG. 8 depicts a cross-sectional view of the coated core particle ofFIG. 5 after coating the other nanoparticles with yet another coating;

FIG. 9 illustrates a cross-sectional view of the coated core particle ofFIG. 8 after still other nanoparticles have been disposed on the yetother coating;

FIG. 10 is a cross-sectional view of the coated core particle of FIG. 9after coating the still other nanoparticles have been coated in a finalcoating;

FIG. 11 depicts a cross-sectional view of a mold that may be used toform a cutting element;

FIG. 12 illustrates a partial cutaway perspective view of a cuttingelement that may be attached to an earth-boring tool; and

FIG. 13 is a perspective view of an earth-boring tool to which cuttingelements may be attached.

DETAILED DESCRIPTION

The illustrations presented herein are not meant to be actual views ofany particular particle, cutting element, or earth-boring tool, but aremerely idealized representations that are employed to describe theembodiments of the disclosure. Thus, the drawings are not necessarily toscale and relative dimensions may have been exaggerated for the sake ofclarity. Additionally, elements common between figures may retain thesame or similar numerical designation.

Embodiments of the disclosure relate to particles of superhard materialthat have nanoparticles coated thereon. In some embodiments, a coatingmaterial comprising an amine terminated group may be successivelyinterposed between the particles and/or the nanoparticles.

The terms “earth-boring tool” and “earth-boring drill bit,” as usedherein, mean and include any type of bit or tool used for drillingduring the formation or enlargement of a wellbore in a subterraneanformation and include, for example, fixed-cutter bits, rolling conebits, impregnated bits, core bits, eccentric bits, bicenter bits, hybridbits as well as reamers, mills, and other drilling bits and tools knownin the art.

As used herein, the term “polycrystalline material” means and includesany structure comprising a plurality of grains (i.e., crystals) ofmaterial (e.g., superhard material) that are bonded directly together byinter-granular bonds. The crystal structures of the individual grains ofthe material may be randomly oriented in space within thepolycrystalline material.

As used herein, the terms “inter-granular bond” and “interbonded” meanand include any direct atomic bond (e.g., covalent, metallic, etc.)between atoms in adjacent grains of superabrasive material.

As used herein, the term “superhard material” means and includes anymaterial having a Knoop hardness value of about 3,000 Kg_(f)/mm² (29,420MPa) or more. Superhard materials include, for example, diamond andcubic boron nitride. Superhard materials may also be characterized as“superabrasive” materials.

As used herein, the terms “nanoparticle” and “nanoscale” mean andinclude any particle, such as, for example, a crystal or grain, havingan average particle diameter of between about 1 nm and 500 nm.

As used herein, the term “tungsten carbide” means any materialcomposition that contains chemical compounds of tungsten and carbon,such as, for example, WC, W₂C, and combinations of WC and W₂C. Tungstencarbide includes, for example, cast tungsten carbide, sintered tungstencarbide, and macrocrystalline tungsten carbide.

Referring to FIG. 1, a cross-sectional view of a core particle 100 isshown. The core particle 100 is shown having a circular cross-sectionfor the sake of simplicity, but core particles 100 in practice may havecross-sections of any shape, including irregular shapes. The coreparticle 100 may comprise a superhard material. For example, the coreparticle 100 may comprise synthetic diamond, natural diamond, cubicboron nitride, or any superhard material known in the art. Thus, thecore particle 100 may comprise a single grain of diamond, for example.The core particle 100 may comprise an average diameter of between 1 μmand 500 μm. The core particle 100 may be provided as one of a pluralityof similar core particles 100. Such a plurality of core particles 100may be free of nanoscale particles.

An outer surface 102 of the core particle 100 may be modified by asurface treatment in some embodiments. For example, the outer surface102 of the core particle 100 may be derivatized to exhibit a netnegative charge or a net positive charge. Thus, a net charge may beimparted to the outer surface 102 of the core particle 100. Surfacetreatment may be accomplished using, for example, corona treatment,plasma treatment, chemical vapor treatment, wet etch, ashing, primertreatment (e.g., polymer-based or organosilane primer treatments), andother surface treatments known in the art.

Referring to FIG. 2, a cross-sectional view of the core particle 100 ofFIG. 1 after being coated with a coating material 104 is shown. Thoughthe coating material 104 is shown as a coating of uniform thicknesscovering the entire outer surface 102 of the core particle 100, thecoating material 104 may be of non-uniform thickness and may cover onlya portion of the outer surface 102 of the core particle 100 in practice.The coating material 104 may carry a net charge opposite the net chargeof the outer surface 102 of the core particle 100, which may facilitateadhesion of the coating material 104 to the outer surface 102 of thecore particle 100, for example, by adsorption. The coating material 104may comprise an amine terminated group. For example, the coatingmaterial 104 may comprise polyallylamine, polyethylenimine,polyethylenamine. As continuing examples, the coating material 104 maycomprise a polyamine prepared by the polymerization of aziridene andincluding polyethylemeamines and polyethylenimines having a branchedstructure derived from aziridene and tris(aminoethyl)amine, ahyperbranched or dendrimeric polyamine such as polyamidoamine (PAMAM)dendrimer, a polyaminoacrylate such aspoly(N,N-dimethylaminoethyl-(meth)acrylate), a copolymer thereof with analkyl or aralkyl (meth)acrylate such as methyl (meth)acrylate, ethyl(meth)acrylate, 2-hydroxypropyl (meth)acrylate, (meth)acrylonitrile,poly(N,N-dimethylaminoethyl-(meth)acrylate)-co-(methyl(meth)acrylate),and combinations comprising at least one of these. As a specificexample, the coating material 104 may comprise polyethylenimine, whichcarries a net positive charge and is water soluble.

The coating material 104 may be disposed on the outer surface 102 of thecore particle 100 by any of several well-known processes. For example,the coating material 104 may be disposed on the outer surface 102 of thecore particle 100 by wet chemistry processes (e.g., dip coating,solid-gel processing, etc.), physical deposition processes (e.g.,sputtering, also known as physical vapor deposition (PVD), etc.),chemical deposition processes (e.g., chemical vapor deposition (CVD),atomic layer deposition (ALD), etc.), or combinations of these. As aspecific example, a plurality of core particles 100 that have beensurface treated using a corona treatment to impart a net negative chargeto the outer surfaces 102 of particles of the plurality of coreparticles 100 may be disposed in an aqueous solution of polyallylamine,which carries a net positive charge, and the polyallylamine may adhereto the outer surfaces 102 of particles of the plurality of coreparticles 100.

Referring to FIG. 3, a cross-sectional view of the coated core particle100 of FIG. 2 after a plurality of nanoparticles 106 has been disposedon the coating material 104 is shown. Though the plurality ofnanoparticles 106 is depicted as having a circular cross-section for thesake of simplicity, the plurality of nanoparticles 106 may comprise anyshape, and specifically may have irregular shapes, in practice. Inaddition, though the plurality of nanoparticles 106 is depicted as beingdisposed on the coating material 104 at fairly regular intervals overthe entire coating material 104, the plurality of nanoparticles 106 maybe disposed on the coating material 104 at irregular intervals and/orover only a portion of the coating material 104. The plurality ofnanoparticles 106 may comprise, for example, surface modifiednanodiamonds, oxidized nanodiamonds, carbon nanotubes, nanographite,nanographene, other nanoscale non-diamond allotropes of carbon (e.g.,amorphous carbon, fullerenes, carbon nanobuds, Lonsdaleite, etc.),nanoscale particles of BeO, and nanoscale particles comprising a GroupVIIIA element (e.g., iron, cobalt, nickel, etc.), known in the art ascatalyst materials. Thus, the material of the plurality of nanoparticles106 may be the same as the material of the core particle 100 in someembodiments. In other embodiments, the plurality of nanoparticles 106may comprise a different material from the material of the core particle100. In some embodiments, the plurality of nanoparticles 106 maycomprise at least some nanoparticles 106 of one material (e.g.,graphite), and at least some other nanoparticles 106 of another material(e.g., a Group VIIIA element catalyst material).

Prior to being deposited onto the coating material 104, the plurality ofnanoparticles 106 may be modified by a surface treatment in someembodiments. For example, an outer surface 108 of the plurality ofnanoparticles 106 may be derivatized to exhibit a net charge opposite anet charge of the coating material 104, which may be a net negativecharge or a net positive charge. Surface treatment may be accomplishedusing, for example, any of the surface treatments described previouslyin connection with the core particle 100 and other surface treatmentsknown in the art. By alternating the net charge carried by thesuccessive components of the coated core particle 100, each successivecomponent (e.g., the core particle 100, the coating material 104, andthe plurality of nanoparticles 106) may be adhered to its adjacentcomponents using non-covalent intermolecular interactions (e.g., van derWaals forces) and mechanical interference.

The plurality of nanoparticles 106 may be disposed on the coatingmaterial 104 by, for example, dispersing the plurality of nanoparticles106 in a continuous phase material to form a dispersion. The resultingdispersion may be, for example, a suspension, a colloid, or a solution,depending on the type of continuous phase material used and the materialof the plurality of nanoparticles 106. As a specific example, theplurality of nanoparticles 106 may comprise carbon nanotubes suspendedin water. The plurality of nanoparticles 106 shown disposed on thecoating material 104 in FIG. 3 may represent only a small proportion ofan overall plurality of nanoparticles 106 in the dispersion to ensurethat a sufficient quantity of nanoparticles 106 is present for adheringto the coating material 104. A plurality of core particles 100 at leastpartially coated with the coating material 104 may then be exposed tothe dispersed plurality of nanoparticles 106 by disposing the pluralityof coated core particles 100 in the dispersion. In some embodiments, thedispersion may then be agitated to circulate the plurality of coatedcore particles 100 and the plurality of nanoparticles 106 and increasethe likelihood that at least some of the plurality of nanoparticles 106may adhere to the coating material 104 disposed on the coated coreparticles 100. As a result, at least some nanoparticles of the pluralityof nanoparticles 106 may be disposed on and adhered to the coatingmaterial 104, which is disposed on and adhered to the plurality of coreparticles 100.

The plurality of nanoparticles 106 may impart desirable characteristicsto the core particle 100. Where the core particle 100 comprises diamondand the plurality of nanoparticles 106 comprises nanographite, forexample, the plurality of nanoparticles 106 may increase the ability tolubricate, increase the electrical insulation, and increase the thermalinsulation of the resulting coated core particle 100 as compared to thecore particle 100 without any nanoparticles 106 coated thereon. Such acombination of characteristics may be desirable in, for example, alubricant in which the coated core particles 100 may be dispersed. Thus,the core particles 100, the coating materials 104, and the nanoparticles106 used will depend on the application for which they are intended andthe properties of each. In some embodiments, a single application ofcoating material 104 and nanoparticles 106 may be sufficient. In otherembodiments, the coated core particle 100 may undergo subsequentprocessing.

Referring to FIG. 4, a cross-sectional view of the coated core particle100 of FIG. 3 is shown after the plurality of nanoparticles 106 has beencoated with a second coating material 104′. Though the second coatingmaterial 104′ is shown as a coating of uniform thickness covering theentire exposed outer surface 108 of the plurality of nanoparticles 106and the underlying coating material 104, the second coating material104′ may be of non-uniform thickness and may cover only a portion of theexposed outer surfaces of components (e.g., the underlying coatingmaterial 104 and the plurality of nanoparticles 106) of the coated coreparticle 100 in practice. The second coating material 104′ may carry anet charge opposite the net charge of the outer surface 108 of theplurality of nanoparticles 106, which may facilitate adhesion of thesecond coating material 104′ to the outer surface 108 of the pluralityof nanoparticles 106, for example, by adsorption. The second coatingmaterial 104′ may comprise an amine terminated group, such as, forexample, any of the amine terminated group materials describedpreviously in connection with the underlying coating material 104. Thesecond coating material 104′ may comprise the same material as theunderlying coating material 104 in some embodiments. In otherembodiments, the second coating material 104′ may comprise a differentmaterial from the underlying coating material 104.

The second coating material 104′ may be disposed on the coated coreparticle 100 by any of several well-known processes. For example, thesecond coating material 104′ may be disposed on the coated core particle100 by any of the processes described previously in connection with theunderlying coating material 104. As a specific example, a plurality ofcoated core particles 100 having a coating material 104 interposedbetween and adhered to each core particle 100 and a plurality ofnanoparticles 106 that have been surface treated using a coronatreatment to impart a net negative charge to the outer surface 108 ofthe plurality of nanoparticles 106 may be disposed in an aqueoussolution of polyallylamine, which carries a net positive charge, and thepolyallylamine may thereby be disposed on and adhered to the outersurface 108 of the plurality of nanoparticles 106.

Referring to FIG. 5, a cross-sectional view of the coated core particle100 of FIG. 4 is shown after a second plurality of nanoparticles 106′has been disposed on the second coating material 104′. Though the secondplurality of nanoparticles 106′ is depicted as having a circularcross-section for the sake of simplicity, the second plurality ofnanoparticles 106′ may comprise any shape, and specifically may haveirregular shapes, in practice. In addition, though the second pluralityof nanoparticles 106′ is depicted as being disposed on the secondcoating material 104′ at fairly regular intervals over the entire secondcoating material 104′, the second plurality of nanoparticles 106′ may bedisposed on the second coating material 104′ at irregular intervals overonly a portion of the second coating material 104′. The second pluralityof nanoparticles 106′ may comprise any of the materials describedpreviously in connection with the first plurality of nanoparticles 106.Thus, the material of the second plurality of nanoparticles 106′ may bethe same as the material of the core particle 100 and the material ofthe first plurality of nanoparticles 106 in some embodiments. In otherembodiments, the second plurality of nanoparticles 106′ may comprise adifferent material from one or both of the materials of the coreparticle 100 and the first plurality of nanoparticles 106. In someembodiments, the second plurality of nanoparticles 106′ may comprise atleast some nanoparticles 106′ of one material (e.g., graphite), and atleast some other nanoparticles 106′ of another material (e.g., a GroupVIIIA element catalyst material). As a specific, non-limiting example,the core particle 100 shown in FIG. 5 may comprise a diamond crystal,the first plurality of nanoparticles 106 may comprise nanographite, andthe second plurality of nanoparticles 106′ may comprise nanographene.

Prior to being deposited onto the second coating material 104′, thesecond plurality of nanoparticles 106′ may be modified by a surfacetreatment in some embodiments. For example, an outer surface 110 of thesecond plurality of nanoparticles 106′ may be derivatized to exhibit anet charge opposite a net charge of the second coating material 104′,which may be a net negative charge or a net positive charge. Surfacetreatment may be accomplished using, for example, any of the surfacetreatments described previously in connection with the core particle 100and other surface treatments known in the art. By alternating the netcharge carried by the successive components of the coated core particle100, each successive component (e.g., the core particle 100, the firstcoating material 104, the first plurality of nanoparticles 106, thesecond coating material 104′, and the second plurality of nanoparticles106′) may be adhered to its adjacent components.

The second plurality of nanoparticles 106′ may be disposed on the secondcoating material 104′ by, for example, dispersing the second pluralityof nanoparticles 106′ in a continuous phase material to form adispersion. The resulting dispersion may be, for example, a suspension,a colloid, or a solution, depending on the type of continuous phasematerial used and the material of the second plurality of nanoparticles106′. As a specific example, the second plurality of nanoparticles 106′may comprise nanoscale particles of cobalt suspended in water. Thesecond plurality of nanoparticles 106′ shown disposed on the secondcoating material 104′ in FIG. 5 may represent only a small proportion ofan overall second plurality of nanoparticles 106′ in the dispersion toensure that a sufficient quantity of nanoparticles 106′ is present foradhering to the second coating material 104′. A plurality of coated coreparticles 100, such as that shown in FIG. 4, may then be exposed to thedispersed second plurality of nanoparticles 106′ by disposing theplurality of coated core particles 100 in the dispersion. In someembodiments, the dispersion may then be agitated to circulate theplurality of coated core particles 100 and the second plurality ofnanoparticles 106′ and increase the likelihood that at least some of thesecond plurality of nanoparticles 106′ may adhere to the second coatingmaterial 104′ disposed on the coated core particles 100. As a result, atleast some of the second plurality of nanoparticles 106′ may be disposedon and adhered to the second coating material 104′.

Referring to FIG. 6, a cross-sectional view of an alternative embodimentof the second plurality of nanoparticles 106′ of FIG. 5 is shown.Specifically, the core particle 100 shown in FIG. 6 may comprise adiamond crystal, the first plurality of nanoparticles 106 may comprisenanographite, and the second plurality of nanoparticles 106′ maycomprise nanoscale particles of cobalt. Such a coated particle may beused as a precursor in a process for making a polycrystalline diamondmaterial of a PDC cutting element. By locating nanoparticles comprisingcarbon allotropes and catalyst material proximate one another andproximate a larger core diamond particle, such a coated core particle100 may facilitate the in situ nucleation of diamond grains. Forexample, the catalyst material of the coated core particle 100 may moreeasily access and catalyze in situ nucleation of diamond grains from thenanographite particles because the catalyst material does not have toflow, as from a cobalt-cemented carbide substrate, through the oftentortuous path to the presence of the nanographite. U.S. ApplicationPublication No. 2011/0031034, published Feb. 10, 2011, now U.S. Pat. No.8,579,052, issued Nov. 12, 2013, the disclosure of which is incorporatedby reference herein in its entirety, discloses that in situ nucleationof diamond grains may result in a stronger and more abrasion resistantpolycrystalline diamond material.

Referring to FIG. 7, a cross-sectional view of another alternativeembodiment of the coated core particle 100 shown in FIG. 5 is shown. Inthis embodiment, the second plurality of nanoparticles 106′ is adhereddirectly to the first plurality of nanoparticles 106. To facilitateadhesion, the second plurality of nanoparticles 106′ may be modified bya surface treatment. For example, the outer surface 110 of the secondplurality of nanoparticles 106′ may be derivatized to exhibit a netcharge opposite a net charge of the outer surface 108 of the firstplurality of nanoparticles 106, which may be a net negative charge or anet positive charge. Surface treatment may be accomplished using, forexample, any of the surface treatments described previously inconnection with the core particle 100 and other surface treatments knownin the art. In embodiments where particles are adhered directly to oneanother, coating materials, such as, for example, the second coatingmaterial 104′ shown in FIGS. 5 and 6 may be omitted. Thus, any of thecoating materials 104 and 104′ described previously and any of thosedescribed subsequently herein may optionally be omitted wherealternating net charge carried by the outer surface or other factorspermit adjacent particles to be directly adhered to one another.

Referring to FIG. 8, a cross-sectional view of the coated core particle100 of FIG. 5 after coating the second plurality of nanoparticles 106′with a third coating material 104″ is shown. Though the third coatingmaterial 104″ is shown as a coating of uniform thickness covering theentire exposed outer surface 110 of the second plurality ofnanoparticles 106′ and the underlying second coating material 104′, thethird coating material 104″ may be of non-uniform thickness and maycover only a portion of the exposed outer surfaces of components (e.g.,the underlying second coating material 104′ and the second plurality ofnanoparticles 106′) of the coated core particle 100 in practice. Thethird coating material 104″ may carry a net charge opposite the netcharge of the outer surface 110 of the second plurality of nanoparticles106′, which may facilitate adhesion of the third coating material 104″to the outer surface 110 of the second plurality of nanoparticles 106′,for example, by adsorption. The third coating material 104″ may comprisean amine terminated group, such as, for example, any of the amineterminated group materials described previously in connection with thefirst coating material 104. The third coating material 104″ may comprisethe same material as the first coating material 104 and the secondcoating material 104′ in some embodiments. In other embodiments, thethird coating material 104″ may comprise a different material from atleast one of the first coating material 104 and the second coatingmaterial 104′.

The third coating material 104″ may be disposed on the coated coreparticle 100 by any of several well-known processes. For example, thethird coating material 104″ may be disposed on the coated core particle100 by any of the processes described previously in connection with thefirst coating material 104. As a specific example, a plurality of coatedcore particles 100 having adhered thereto an outer second plurality ofnanoparticles 106′ that have been surface treated using a coronatreatment to impart a net negative charge to the outer surface 110 ofthe second plurality of nanoparticles 106′ may be disposed in an aqueoussolution of polyallylamine, which carries a net positive charge, and thepolyallylamine may thereby be disposed on and adhered to the outersurface 110 of the second plurality of nanoparticles 106′.

Referring to FIG. 9, a cross-sectional view of the coated core particle100 of FIG. 8 is shown after a third plurality of nanoparticles 106″ hasbeen disposed on the third coating material 104″. Though the thirdplurality of nanoparticles 106″ is depicted as having a circularcross-section for the sake of simplicity, the third plurality ofnanoparticles 106″ may comprise any shape, and specifically may haveirregular shapes, in practice. In addition, though the third pluralityof nanoparticles 106″ is depicted as being disposed on the third coatingmaterial 104″ at fairly regular intervals over the entire third coatingmaterial 104″, the third plurality of nanoparticles 106″ may be disposedon the third coating material 104″ at irregular intervals over only aportion of the third coating material 104″. The third plurality ofnanoparticles 106″ may comprise any of the materials describedpreviously in connection with the first plurality of nanoparticles 106.Thus, the material of the third plurality of nanoparticles 106″ may bethe same as the material of the core particle 100, the material of thefirst plurality of nanoparticles 106, and the material of the secondplurality of nanoparticles 106′ in some embodiments. In otherembodiments, the third plurality of nanoparticles 106″ may comprise adifferent material from one, some, or all of the materials of the coreparticle 100, the first plurality of nanoparticles 106, and the secondplurality of nanoparticles 106′. In some embodiments, the thirdplurality of nanoparticles 106″ may comprise at least some nanoparticles106″ of one material (e.g., graphite), and at least some othernanoparticles 106″ of another material (e.g., a Group VIIIA elementcatalyst material). As a specific non-limiting example, the coreparticle 100 shown in FIG. 9 may comprise a diamond crystal, the firstplurality of nanoparticles 106 may comprise nanographite, the secondplurality of nanoparticles 106′ may comprise nanographene, and the thirdplurality of particles 106″ may comprise carbon nanotubes.

Prior to being deposited onto the third coating material 104″, the thirdplurality of nanoparticles 106″ may be modified by a surface treatmentin some embodiments. For example, an outer surface 112 of the thirdplurality of nanoparticles 106″ may be derivatized to exhibit a netcharge opposite a net charge of the third coating material 104″, whichmay be a net negative charge or a net positive charge. Surface treatmentmay be accomplished using, for example, any of the surface treatmentsdescribed previously in connection with the core particle 100 and othersurface treatments known in the art. By alternating the net chargecarried by the successive components of the coated core particle 100,each successive component (e.g., the core particle 100, the firstcoating material 104, the first plurality of nanoparticles 106, thesecond coating material 104′, the second plurality of nanoparticles106′, the third coating material 104″, and the third plurality ofparticles 106″) may be adhered to its adjacent components.

The third plurality of nanoparticles 106″ may be disposed on the thirdcoating material 104″ by, for example, dispersing the third plurality ofnanoparticles 106″ in a continuous phase material to form a dispersion.The resulting dispersion may be, for example, a suspension, a colloid,or a solution, depending on the type of continuous phase material usedand the material of the third plurality of nanoparticles 106″. As aspecific example, the third plurality of nanoparticles 106″ may comprisenanoscale particles of BeO suspended in water. The third plurality ofnanoparticles 106″ shown disposed on the third coating material 104″ inFIG. 9 may represent only a small proportion of an overall thirdplurality of nanoparticles 106″ in the dispersion to ensure that asufficient quantity of nanoparticles 106″ is present for adhering to thethird coating material 104″. A plurality of coated core particles 100,such as coated core particle 100 shown in FIG. 8, may then be exposed tothe dispersed third plurality of nanoparticles 106″ by disposing theplurality of coated core particles 100 in the dispersion. In someembodiments, the dispersion may then be agitated to circulate theplurality of coated core particles 100 and the third plurality ofnanoparticles 106″ and increase the likelihood that at least some of thethird plurality of nanoparticles 106″ may adhere to the third coatingmaterial 104″ disposed on the plurality of coated core particles 100. Asa result, at least some of the third plurality of nanoparticles 106″ maybe disposed on and adhered to the third coating material 104″.

Referring to FIG. 10, a cross-sectional view of the coated core particle100 of FIG. 9 after coating the third plurality of nanoparticles 106″with a fourth coating material 104′″ is shown. Though the fourth coatingmaterial 104′″ is shown as a coating of uniform thickness covering theentire exposed outer surface 112 of the third plurality of nanoparticles106″ and the underlying third coating material 104″, the fourth coatingmaterial 104′″ may be of non-uniform thickness and may cover only aportion of the exposed outer surfaces of components (e.g., theunderlying third coating material 104″ and the third plurality ofnanoparticles 106″) of the coated core particle 100 in practice. Thefourth coating material 104′″ may carry a net charge opposite the netcharge of the outer surface 112 of the third plurality of nanoparticles106″, which may facilitate adhesion of the fourth coating material 104′″to the outer surface 112 of the third plurality of nanoparticles 106″,for example, by adsorption. The fourth coating material 104′″ maycomprise an amine terminated group, such as, for example, any of theamine terminated group materials described previously in connection withthe first coating material 104. The fourth coating material 104′″ maycomprise the same material as the first coating material 104, the secondcoating material 104′, and the third coating material 104″ in someembodiments. In other embodiments, the third coating material 104″ maycomprise a different material from at least one of the first coatingmaterial 104, the second coating material 104′, and the third coatingmaterial 104″.

The fourth coating material 104′″ may be disposed on the coated coreparticle 100 by any of several well-known processes. For example, thefourth coating material 104′″ may be disposed on the coated coreparticle 100 by any of the processes described previously in connectionwith the first coating material 104. As a specific example, a pluralityof coated core particles 100 having adhered thereto an outer thirdplurality of nanoparticles 106″ that has been surface treated using acorona treatment to impart a net negative charge to the outer surface112 of the third plurality of nanoparticles 106″ may be disposed in anaqueous solution of polyallylamine, which carries a net positive charge,and the polyallylamine may thereby be disposed on and adhered to theouter surface 112 of the third plurality of nanoparticles 106″.

Successive deposition of pluralities of nanoparticles and coatingmaterials, a process known in the art as layer-by-layer or “LbL”deposition, may continue for as many times as desired or practicable.For example, fourth, fifth, sixth, seventh, etc., pluralities ofnanoparticles may be disposed on fourth, fifth, sixth, seventh, etc.,coating materials. Such subsequent deposition of pluralities ofnanoparticles and coating materials may comprise materials and may beaccomplished using processes such as those described previously inconnection with the first plurality of nanoparticles 106 and the firstcoating material 104 (FIG. 3).

After a desired number of iterations of deposition of coating materialsand pluralities of nanoparticles has occurred, the coating materials maybe cross-linked. Cross-linking the coating materials may enhance themechanical strength and stability of the coating materials.Cross-linking may be accomplished using, for example, addition of across-linking reagent, ultraviolet radiation, electron beam radiation,heat, or other processes for cross-linking known in the art.

FIG. 11 depicts a cross-sectional view of a mold 114 that may be used toform a cutting element. The mold 114 may include one or more generallycup-shaped members, such as a cup-shaped member 114 a, a cup-shapedmember 114 b, and a cup-shaped member 114 c, which may be assembled andswaged and/or welded together to form the mold 114. A plurality ofparticles 116 comprising a superhard material may be disposed within theinner cup-shaped member 114 c, as shown in FIG. 11, which has a circularend wall and a generally cylindrical lateral side wall extendingperpendicularly from the circular end wall, such that the innercup-shaped member 114 c is generally cylindrical and includes a firstclosed end and a second, opposite open end.

The plurality of particles 116 may comprise at least one coatedparticle, such as any of those shown in FIGS. 3 through 10. In someembodiments, each particle of the plurality of particles 116 maycomprise a coated particle similar to the other coated particles of theplurality of coated particles. In other embodiments, at least some ofthe particles may comprise coated particles with a different number ofcoatings and/or a different combination of materials than others of theparticles of the plurality of particles 116. In still other embodiments,coated particles, such as any of those shown in FIGS. 3 through 10, maybe intermixed with or interlayered with uncoated particles, such as thatshown in FIG. 1, within the plurality of particles 116. In someembodiments, an optional catalyst material 118 in the form of a powdermay be interspersed among the plurality of particles 116 comprising asuperhard material. The plurality of particles 116 may comprise amono-modal or a multi-modal grain size distribution.

A substrate 120 comprising a hard material suitable for use inearth-boring applications may be disposed adjacent the plurality ofparticles 116 in the mold 114. The hard material of the substrate 120may comprise, for example, a ceramic-metal composite material (i.e., a“cermet” material) comprising a plurality of hard ceramic particlesdispersed throughout a metal matrix material. The hard ceramic particlesmay comprise carbides, nitrides, oxides, and borides (including boroncarbide (B₄C)). More specifically, the hard ceramic particles maycomprise carbides and borides made from elements such as W, Ti, Mo, Nb,V, Hf, Ta, Cr, Zr, Al, and Si. By way of example and not limitation,materials that may be used to form hard ceramic particles includetungsten carbide, titanium carbide (TiC), tantalum carbide (TaC),titanium diboride (TiB₂), chromium carbides, titanium nitride (TiN),aluminum oxide (Al₂O₃), aluminum nitride (AlN), and silicon carbide(SiC). The metal matrix material of the ceramic-metal composite materialmay include, for example, cobalt-based, iron-based, nickel-based, iron-and nickel-based, cobalt- and nickel-based, and iron- and cobalt-basedalloys. The matrix material may also be selected from commercially pureelements such as cobalt, iron, and nickel. As a specific, non-limitingexample, the hard material may comprise a plurality of tungsten carbideparticles in a cobalt matrix, known in the art as cobalt-cementedtungsten carbide.

The plurality of particles 116, the optional catalyst material 118, andthe substrate 120 may then be subjected to a high temperature/highpressure (HTHP) process. Although the exact operating parameters of HTHPprocesses will vary depending on the particular compositions andquantities of the various materials being sintered, the pressures in theheated press may be greater than about 5.0 GPa and the temperatures maybe greater than about 1,400° C. The pressures in the heated press may begreater than about 6.5 GPa (e.g., about 6.7 GPa), and may even exceed8.0 GPa in some embodiments. Furthermore, the materials being sinteredmay be held at such temperatures and pressures for a time period betweenabout 30 seconds and about 20 minutes. If necessary or desirable, thetemperature may be reduced to about 1,000° C. and held for up to aboutone hour, or more to assist in the in situ nucleation of grains ofsuperhard material. Additionally, the temperature may be reduced andmaintained at a temperature between about 400° C. and about 800° C. forat least about 30 minutes (e.g., up to about 24 hours or more) in aprocess similar to those known in the art of metallurgy as“re-crystallization annealing” process.

Referring to FIG. 12, a partial cutaway perspective view of a cuttingelement 122 formed by an HTHP process is shown. The cutting element 122includes a polycrystalline table 124 attached to an end of a substrate120. The polycrystalline table 124 comprises a polycrystalline superhardmaterial, such as, for example, polycrystalline diamond. Though thecutting element 122 is depicted as having a cylindrical shape, coatedcore particles, such as any of those shown in FIGS. 3 through 10, may beused to form polycrystalline tables 124 having any shape, such as, forexample, dome-shaped, conic, tombstone, and other shapes for superhardpolycrystalline materials known in the art.

Referring to FIG. 13, a perspective view of an earth-boring tool 126 towhich cutting elements 122 may be attached is shown. The earth-boringtool 126 includes a bit body 128 having blades 130 extending from thebit body 128. The cutting elements 122 may be secured within pockets 132formed in the blades 130. However, cutting elements 122 andpolycrystalline tables 124 as described herein may be bonded to and usedon other types of earth-boring tools, including, for example, rollercone drill bits, percussion bits, impregnated bits, core bits, eccentricbits, bicenter bits, reamers, expandable reamers, mills, hybrid bits,and other drilling bits and tools known in the art.

While the present invention has been described herein with respect tocertain embodiments, those of ordinary skill in the art will recognizeand appreciate that it is not so limited. Rather, many additions,deletions, and modifications to the embodiments described herein may bemade without departing from the scope of the invention as hereinafterclaimed, including legal equivalents. In addition, features from oneembodiment may be combined with features of another embodiment whilestill being encompassed within the scope of the invention ascontemplated by the inventor.

CONCLUSION

In some embodiments, coated particles comprise a core particlecomprising a superhard material and having an average diameter ofbetween 1 μm and 500 μm. A coating material is adhered to and covers atleast a portion of an outer surface of the core particle, the coatingmaterial comprising an amine terminated group. A plurality ofnanoparticles selected from the group consisting of carbon nanotubes,nanographite, nanographene, non-diamond carbon allotropes, surfacemodified nanodiamond, nanoscale particles of BeO, and nanoscaleparticles comprising a Group VIIIA element is adhered to the coatingmaterial.

In other embodiments, methods of coating a particle comprise at leastpartially coating a core particle comprising a superhard material andhaving an average diameter of between 1 μm and 500 μm with a coatingmaterial comprising an amine terminated group. The coating materialadheres to an outer surface of the core particle. The at least partiallycoated core particle is disposed in a dispersion comprising a pluralityof nanoparticles comprising a material selected from the groupconsisting of graphite, graphene, a non-diamond allotrope of carbon,surface modified diamond, BeO, and a Group VIIIA element dispersed in acontinuous phase material. At least some nanoparticles of the pluralityof nanoparticles adhere to the coating material.

In additional embodiments, methods of forming a polycrystalline compactcomprise at least partially coating a plurality of core particlescomprising a superhard material and having an average particle size ofbetween 1 μm and 500 μm with a coating material comprising an amineterminated group. The coating material adheres to an outer surface ofthe plurality of core particles. The at least partially coated pluralityof core particles is disposed in a dispersion comprising a plurality ofnanoparticles comprising a material selected from the group consistingof graphite, graphene, a non-diamond allotrope of carbon, surfacemodified diamond, BeO, and a Group VIIIA element dispersed in acontinuous phase material. At least some nanoparticles of the pluralityof nanoparticles adhere to the coating material. At least some of the atleast partially coated plurality of core particles are interbonded bysubjecting them to a high temperature/high pressure process to form apolycrystalline material.

What is claimed is:
 1. A coated particle, comprising: a core particlecomprising a superhard material and having an average diameter ofbetween 1 μm and 500 μm; a coating material adhered to and covering atleast a portion of an outer surface of the core particle, the coatingmaterial comprising an amine terminated group; and a plurality ofnanoparticles selected from the group consisting of carbon nanotubes,nanographite, nanographene, non-diamond carbon allotropes, surfacemodified nanodiamond, nanoscale particles of BeO, and nanoscaleparticles comprising a Group VIIIA element adhered to the coatingmaterial, at least a portion of the plurality of nanoparticlescomprising a different material than the superhard material of the coreparticle.
 2. The coated particle of claim 1, wherein the outer surfaceof the core particle comprises a first net charge, the coating materialcomprises a second net charge opposite the first net charge, and anouter surface of at least some nanoparticles of the plurality ofnanoparticles comprises a third net charge opposite the second netcharge.
 3. The coated particle of claim 1, further comprising at least asecond coating material adhered to and covering at least a portion ofthe plurality of nanoparticles.
 4. The coated particle of claim 3,further comprising at least a second plurality of nanoparticles selectedfrom the group consisting of carbon nanotubes, nanographite,nanographene, non-diamond carbon allotropes, surface modifiednanodiamond, nanoscale particles of BeO, and nanoscale particlescomprising a Group VIIIA element adhered to the at least a secondcoating material.
 5. The coated particle of claim 4, wherein theplurality of nanoparticles comprises a material different from thematerial of the at least a second plurality of nanoparticles.
 6. Thecoated particle of claim 4, wherein the core particle, the coatingmaterial, the plurality of nanoparticles, the at least a second coatingmaterial, and the at least a second plurality of nanoparticles comprisea net charge opposite a net charge of their adjacent components.
 7. Thecoated particle of claim 4, further comprising a plurality of othercoating materials and other pluralities of nanoparticles successivelydisposed on and adhered to one another.
 8. The coated particle of claim1, wherein the coating material comprises at least one of polyallylamineand branched polyethylenimine.
 9. A method of coating a particle,comprising: at least partially coating a core particle comprising asuperhard material and having an average diameter of between 1 μm and500 μm with a coating material comprising an amine terminated group;adhering the coating material to an outer surface of the core particle;disposing the at least partially coated core particle in a dispersioncomprising a plurality of nanoparticles, at least a portion of theplurality of nanoparticles comprising a material different than thesuperhard material of the core particle and selected from the groupconsisting of graphite, graphene, a non-diamond allotrope of carbon,surface modified diamond, BeO, and a Group VIIIA element dispersed in acontinuous phase material; and adhering at least some nanoparticles ofthe plurality of nanoparticles to the coating material.
 10. The methodof claim 9, further comprising: imparting a first net charge opposite asecond net charge of the coating material to the outer surface of thecore particle; and imparting a third net charge opposite the second netcharge to an outer surface of at least some nanoparticles of theplurality of nanoparticles.
 11. The method of claim 9, furthercomprising: at least partially coating the at least some nanoparticlesof the plurality of nanoparticles with a coating material comprising anamine terminated group; and adhering the coating material to the atleast some nanoparticles of the plurality of nanoparticles.
 12. Themethod of claim 11, further comprising: disposing the core particle, thecoating material, and the at least some nanoparticles of the pluralityof nanoparticles in a dispersion comprising another plurality ofnanoparticles comprising a material selected from the group consistingof graphite, graphene, a non-diamond allotrope of carbon, surfacemodified diamond, BeO, and a Group VIIIA element dispersed in acontinuous phase material; and adhering at least some nanoparticles ofthe another plurality of nanoparticles to the coating material.
 13. Themethod of claim 12, wherein disposing the core particle, the coatingmaterial, and the at least some nanoparticles of the plurality ofnanoparticles in a dispersion comprising another plurality ofnanoparticles comprising a material selected from the group consistingof graphite, graphene, a non-diamond allotrope of carbon, surfacemodified diamond, BeO, and a Group VIIIA element dispersed in acontinuous phase material comprises disposing the core particle, thecoating material, and the at least some nanoparticles of the pluralityof nanoparticles in a dispersion comprising another plurality ofnanoparticles comprising a material different from the material of theat least some nanoparticles of the plurality of nanoparticles.
 14. Themethod of claim 12, further comprising repeating the acts of at leastpartially coating, adhering, disposing in a dispersion, and adhering apredetermined number of times.
 15. The method of claim 9, furthercomprising derivatizing the outer surface of the core particle before atleast partially coating the core particle.
 16. The method of claim 9,further comprising derivatizing an outer surface of the plurality ofnanoparticles before disposing the at least partially coated coreparticle in the dispersion comprising the plurality of nanoparticles.17. The method of claim 9, further comprising: disposing the coreparticle, the coating material, and the at least some nanoparticles ofthe plurality of nanoparticles in a dispersion comprising a plurality ofnanoparticles comprising a material selected from the group consistingof graphite, graphene, a non-diamond allotrope of carbon, surfacemodified diamond, BeO, and a Group VIIIA element dispersed in acontinuous phase material, wherein the plurality of nanoparticlescomprises a charge opposite a charge of the at least some of thenanoparticles; and adhering at least some other nanoparticles of theplurality of nanoparticles to the at least some nanoparticles of thenanoparticles.
 18. The method of claim 9, further comprisingcross-linking the coating material.
 19. The method of claim 9, whereinat least partially coating a core particle comprising a superhardmaterial and having an average diameter of between 1 μm and 500 μm witha coating material comprising an amine terminated group comprises atleast partially coating the core particle with at least one ofpolyallylamine and branched polyethylenimine.
 20. A method of forming apolycrystalline compact, comprising: at least partially coating aplurality of core particles comprising a superhard material and havingan average particle size of between 1 μm and 500 μm with a coatingmaterial comprising an amine terminated group; adhering the coatingmaterial to an outer surface of the plurality of core particles;disposing the at least partially coated plurality of core particles in adispersion comprising a plurality of nanoparticles, at least a portionof the plurality of nanoparticles comprising a different material thanthe superhard material of the core particles and selected from the groupconsisting of graphite, graphene, a non-diamond allotrope of carbon,surface modified diamond, BeO, and a Group VIIIA element dispersed in acontinuous phase material; adhering at least some nanoparticles of theplurality of nanoparticles to the coating material; and interbonding atleast some at least partially coated core particles of the at leastpartially coated plurality of core particles by subjecting them to ahigh temperature/high pressure process to form a polycrystallinematerial.
 21. The method of claim 20, further comprising: imparting afirst net charge opposite a second net charge of the coating material tothe outer surface of the plurality of core particles; and imparting athird net charge opposite the second net charge to an outer surface ofat least some nanoparticles of the plurality of nanoparticles.
 22. Themethod of claim 20, further comprising at least partially coating the atleast some nanoparticles of the plurality of nanoparticles with acoating material comprising an amine terminated group.
 23. The method ofclaim 22, further comprising: disposing the plurality of core particles,the coating material, and the at least some nanoparticles of theplurality of nanoparticles in a dispersion comprising another pluralityof nanoparticles comprising a material selected from the groupconsisting of graphite, graphene, a non-diamond allotrope of carbon,surface modified diamond, BeO, and a Group VIIIA element dispersed in acontinuous phase material; and adhering at least some nanoparticles ofthe another plurality of nanoparticles to the coating material.
 24. Themethod of claim 23, wherein disposing the plurality of core particles,the coating material, and the at least some nanoparticles of theplurality of nanoparticles in a dispersion comprising another pluralityof nanoparticles comprising a material selected from the groupconsisting of graphite, graphene, a non-diamond allotrope of carbon,surface modified diamond, BeO, and a Group VIIIA element dispersed in acontinuous phase material comprises disposing the plurality of coreparticles, the coating material, and the at least some nanoparticles ofthe plurality of nanoparticles in a dispersion comprising anotherplurality of nanoparticles comprising a material different from thematerial of the at least some nanoparticles of the plurality ofnanoparticles.